Calculate total static pressure for dust collection systems based on duct length, fittings, and components.
Enter system parameters to calculate total static pressure.
Static pressure (SP) measures resistance to airflow in your dust collection system. It is measured in inches of water column ("). Higher SP means more resistance. Your collector must overcome total SP to deliver adequate airflow.
Total SP = Duct Friction + Fitting Losses + Filter Resistance | Fitting | Pressure Loss | Equivalent Length | Notes |
|---|---|---|---|
| 90° Elbow (smooth) | ~2.5" | 12-15 ft | Use long-radius when possible |
| 45° Elbow | ~1.2" | 6-8 ft | Preferred over 90° bends |
| Y-Branch | ~1.5" | 8-10 ft | Better than T-connections |
| Blast Gate (open) | ~0.5" | 2-3 ft | Keep gates open only for active tools |
| Flexible Hose (per ft) | ~0.15" | 1.5 ft | Use shortest length possible |
Resistance to airflow measured in inches of water column ("). Total SP determines how hard the collector must work to move air through the system.
Volume of air moved per minute. Dust collectors are rated at specific CFM/SP combinations. Higher SP reduces actual CFM delivery.
Length of straight duct that would produce the same pressure loss as a fitting. Used to convert fittings to total duct length for calculations.
Pressure caused by air movement. Combined with static pressure to give total pressure. Important for maintaining transport velocity to keep chips moving.
Minimum air speed needed to keep dust/chips suspended in the duct. Typically 3500-4500 FPM for woodworking dust. Below this, chips settle and clog ducts.
Check manufacturer performance curves. Most 1.5-2HP collectors are rated for 6-8" SP. Beyond rated SP, CFM drops dramatically. If calculated SP exceeds 80% of rated maximum, consider redesigning ductwork or upgrading the collector.
Larger ducts dramatically reduce friction: 6" duct at 800 CFM has ~0.3"/ft friction vs ~1.2"/ft for 4" duct. Doubling diameter reduces friction by ~75%. Use the largest diameter practical for main runs.
Smooth metal duct whenever possible. Corrugated flex hose has 2-3x the friction of smooth duct. Limit flex hose to short final connections (under 6 feet) at individual tools.
Use a manometer or magnehelic gauge. Drill a small hole in the duct near the collector inlet and measure. Compare actual SP to calculated values. Significant differences indicate leaks, clogs, or design issues.
Add 20-25% safety margin to calculated SP for filter loading, future expansion, and calculation uncertainty. If calculated SP is 6", select a collector rated for at least 7.5" SP at your required CFM.
Opening more gates reduces SP per branch but increases total CFM demand. Your collector has a fixed CFM/SP relationship. Running too many open gates may reduce velocity below transport speed, causing clogs.